Amateur career

Johnson was an amateur standout, and was the 1989 United States Amateur Light flyweight champion.

Professional career

Johnson, nicknamed "Too Sharp", defeated Francisco Tejedor to win the IBFFlyweight title in 1996. Although he never attained significant popularity due to his weight class and lack of defining fights, he went on to become one of the top pound for pound fighters in boxing for several years. Johnson defended the Flyweight title seven times before moving up in weight to win the IBF Super Flyweight title in 1999 via unanimous decision over Ratanachai Vor Vorapin. He defended the Super Flyweight title twice before moving up again to Bantamweight.

In his third fight at Bantamweight Johnson lost in an upset to up and coming Rafael Marquez by split decision over 10 rounds in 2001. This bout was clouded by the fact that Johnson was deducted two points for holding. In the rematch the following year, Marquez took Johnson apart, winning by TKO in the 8th round. Johnson never regained his stature following the losses, although he did upset WBO Super Flyweight champion Fernando Montiel in 2003. Johnson went on to lose by KO in the 8th round to both Ivan Hernández for the WBO Super Flyweight and Jhonny González, signaling the end to Johnson's illustrious career.